Geminale Substituenteneffekte. VIII. Standardbildungsenthalpien von Acetalen
作者:Sergey P. Verevkin、Barbara Dogan、Johannes H�drich、Hans-Dieter Beckhaus、Christoph R�chardt
DOI:10.1002/prac.19953370122
日期:——
The standard enthalpies of combustion Delta H-c degrees (1 or c) of the alpha-phenyl-substituted acetals (1) and diacetals (2) were measured calorimetrically The enthalpies of vaporisation or sublimation Delta H-vap or Delta H-sub of 1-2 were obtained from the temperature function of the vapor pressure measured in a flow system, and the standard enthalpies of formation are obtained thereof: Delta H-f degrees (1 or c) and Delta H-f degrees (g) (in kJ mol(-1) for 1a = -308.40 +/- 0.52(1), -248.94 +/- 0.88; 1b = -343.48 +/- 0.72 (1), -288.5 +/- 1.5; 1c = -267.4 +/- 1.3 (1), -205.3 +/- 1.3; 1d = -343.8 +/- 2.1 (c), -261.9 +/- 2.2; 1e = -397.02 +/- 0.86 (c), -311.3 +/- 1.2; 1f = -414.52 +/- 0.80 (1), -350.68 +/- 0.86; 2a = -564.8 +/- 2.4 (c), -467.1 +/- 2.5; 2b = -547.6 +/- 1.6 (c), -414.9 +/- 2.7; 2c = -717.1 +/- 7.5 (c), -587.0 +/- 8.0. The results are combined into values of two strain free group increments CH[20, C-Ph] = -59.7 and C[20, C-Ph, C] = -71.3 kJ mol(-1); and compared to the aliphatic series of acetals.